package juc;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

class MyCache{
    private volatile Map<String,Object> map = new HashMap<>();

    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    public void put(String key,Object value){


        readWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "\t ---开始写入" + key);
            try {
                TimeUnit.MILLISECONDS.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            map.put(key,value);
            System.out.println(Thread.currentThread().getName() + "\t ---写入完成");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            readWriteLock.writeLock().unlock();
        }
    }

    public void get(String key){

        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "\t 开始读取");
            try {
                TimeUnit.MILLISECONDS.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            Object value = map.get(key);
            System.out.println(Thread.currentThread().getName() + "\t 读取完成" + value);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            readWriteLock.readLock().unlock();
        }

    }
}

public class ReadWriteLockDemo {
    public static void main(String args[]){
        MyCache myCache = new MyCache();

        for (int i = 0; i < 5; i++) {
            final int tmp = i;
            new Thread(() -> {
                myCache.put(tmp+"",tmp+"");
            },String.valueOf(i)).start();
        }

        for (int i = 0; i < 5; i++) {
            final int tmp = i;
            new Thread(() -> {
                myCache.get(tmp+"");
            },String.valueOf(i)).start();
        }
    }
}
